Linux-ACPI Archive on
 help / color / Atom feed
From: Sakari Ailus <>
To: Wolfram Sang <>,,
	"Rafael J. Wysocki" <>,, Bingbu Cao <>,,
	Chiranjeevi Rapolu <>,
	Hyungwoo Yang <>,
	Bartosz Golaszewski <>,
	Arnd Bergmann <>,,
	Greg Kroah-Hartman <>,, Tomasz Figa <>,
	"Qiu, Tian Shu" <>
Subject: Re: [PATCH v6 1/6] i2c: Allow an ACPI driver to manage the device's power state during probe
Date: Mon, 31 Aug 2020 12:54:15 +0300
Message-ID: <> (raw)
In-Reply-To: <20200831093109.GA4632@kunai>

On Mon, Aug 31, 2020 at 11:31:09AM +0200, Wolfram Sang wrote:
> > This patchset is really about changing the default of ACPI powering up I²C
> > devices. On OF the drivers are indeed responsible for that.
> So, maybe it makes sense then to move from 'device_property_present()'
> to 'acpi_dev_get_property()' or something alike? To clearly tell this

I'll do that for v7 soon.

> binding is expected to be used with ACPI only. Then, we can skip this
> discussion now and postpone it to when someone wants to use it with DT.
> Which is hopefully never. Or does this approach have drawbacks?

The same issue in principle could be there on DT, too, as the cameras are
the same. There are a few sensor drivers supporting DT that currently don't
access the device in probe to avoid having to power it on. For cameras I
suppose that's just fine but I'd be hesitant changing the behaviour of e.g.
the at24 driver to support that use case without making it somehow

> > My original series had a field in struct device_driver for this purpose but
> > Greg K-H suggested moving it to I²C instead:
> > 
> > <URL:>
> Ok, we can still factor it out in the unlikely case it needs to be done
> again.
> I still have the question via which tree this should go upstream?
> It is probably more I2C than ACPI?

I think so.

Rafael, would you be fine with this set being merged through the I²C tree?
There's a single patch adding an ACPI function there.

Sakari Ailus

  reply index

Thread overview: 16+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-08-26 11:54 [PATCH v6 0/6] Support running driver's probe for a device powered off Sakari Ailus
2020-08-26 11:54 ` [PATCH v6 1/6] i2c: Allow an ACPI driver to manage the device's power state during probe Sakari Ailus
2020-08-28  8:38   ` Wolfram Sang
2020-08-31  8:23     ` Sakari Ailus
2020-08-31  9:31       ` Wolfram Sang
2020-08-31  9:54         ` Sakari Ailus [this message]
2020-08-31 10:00   ` Wolfram Sang
2020-08-31 17:05     ` Sakari Ailus
2020-08-26 11:54 ` [PATCH v6 2/6] ACPI: Add a convenience function to tell a device is in low power state Sakari Ailus
2020-08-26 11:54 ` [PATCH v6 3/6] ov5670: Support probe whilst the device is in a " Sakari Ailus
2020-08-26 11:54 ` [PATCH v6 4/6] media: i2c: imx319: Support probe while the device is off Sakari Ailus
2020-08-26 11:54 ` [PATCH v6 5/6] at24: Support probing while off Sakari Ailus
2020-08-26 11:54 ` [PATCH v6 6/6] Documentation: ACPI: Document allow-low-power-probe _DSD property Sakari Ailus
2020-08-26 18:06   ` Randy Dunlap
2020-08-27 13:28     ` Sakari Ailus
2020-09-01 20:28       ` Sakari Ailus

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

Linux-ACPI Archive on

Archives are clonable:
	git clone --mirror linux-acpi/git/0.git

	# If you have public-inbox 1.1+ installed, you may
	# initialize and index your mirror using the following commands:
	public-inbox-init -V2 linux-acpi linux-acpi/ \
	public-inbox-index linux-acpi

Example config snippet for mirrors

Newsgroup available over NNTP:

AGPL code for this site: git clone